API 650 unanchored liquid-storage tanks wax scrapers

Define the welding sequence of API 650 unanchored liquid-storage tanks bottom plate: the welding sequence of metal vertical storage tank shall be carried out according to the procedure required by the welding scheme. Spot welding shall be consistent with the formal welding requirements, and no spot welding shall be carried out for the weld not welded. Back bar should be added to prevent deformation when welding the full length seam of middle plate, butt joint of edge plate and turtle shell joint.

Temporary Openings after Hydrostatic Test
When approved by the Purchaser in writing, and only in the case of tanks which when complete have no shell penetrations, it is permitted to restore by welding up to four temporary shell openings after the hydrostatic test in accordance with the provisions of this section. Each temporary opening shall be restored by the insertion of a shell plate that matches the thickness and specification of adjacent shell material, and is welded into place with full fusion butt-welds. The API 650 unanchored liquid-storage tanks insert plate shall be round with diameter no less than 24 in. and no greater than 42 in.

For open top and fixed roof API 650 tanks, the net working capacity is the liquid volume contained between the minimum operating level (top of API 650 tanks API 650 unanchored liquid-storage tanks outlet connection) and the maximum operating level [limited to the bottom of overflow connection, 75 mm below foam chamber connection, or 150 mm below rim, whichever is greater.